Tap changing switch and system



July 12, 1932. A. HALLER 1,867,147

' TAP CHANGING SWITCH AND SYSTEM Filed May 29, 1931 3 Sheets-Sheet l 9b 36 9 5 \HA A A Fig. 1'.

Inventor Amald Haller Byw Aitomgr July 12, 1932. A. HALLER 1,867,147

TAP CHANGING SWITCH AND SYSTEM Filed May 29, 1951 5 Sheets-Sheet 2 [mentor Arnold Haller July 12, 1932. A. HALLER TAP CHANGING SWITCH AND SYSTEM Filed May 29, 1981 3 Sheets-Sheet 5 ZIQI mm 44' M F'l the carriage over circularly Patented July 12, 1932 PATENT OFFICE ARNOLD HALLER, or BADE'N, "SWITZERLAND, AssIGNoR r0 AKTIENGESELLSCHAFT BROWN BOVERI & c111, or

SWITZERLAND 'sAnnn, SWITZERLAND, A JOINT srocx' COMPANY, or

TAP orrANeme SWITCH AND 'sYs'rnM Application filed May 29, 1931 Serial No. 540,964, and in Germany June 10, 1930.

, This invention relates to improvements in means for obtaining a step-wise operation of a switching device, such as a tap switch, in both directions of movement. 1 v i c In the use of electrical apparatus such as transformers particularly when applied for traction purposes as in an electric locomotive, a tap switch having a large number of steps is required to obtain proper regulation of the voltage supplied to the traction motors. The contacts may then be arranged in a circle to economize space and the brushes sliding on the contacts may be rotated by a motor or other suitable drives. It is, however, necessary that movement of the brushes from one contact to the other he made without interruption of current, without sparking at the contactsand'at a non-uniform rate of movement throughout the various portions of the rotary movement.

It is, therefore, among the objects of the present invention to provide a tap switch in which a portion of the contacts are formed as continuous circular bars and the separate contacts are lilrewise arranged in a circle.

Another obyect of the invention is to provide a tap switch in which movable'contacts are rolled over circularly arranged fixed con-' tacts in steps at a rate which is not uniform throughout the entire path of travel.

Another object of the invention is to provide a tap switch in which movable contacts are automatically returned to a neutral posi tion between movements over the fixed con vide a tap switch in which movable contacts are rotatably mounted on a carriagewhich moves over circularly arranged fixed contacts. I I

Another object of theinventlon 1s to provide a tap switch in whichmovable contacts are mounted on a carriage resiliently con-' nected at three points'with means for moving arranged fixed contacts.

Objects and advantages, other those J above set forth, will be apparent from theafollowing description when read in connection with the accompanying drawings in which path for their magnetic circuits.

Figure 1 diagrammatically illustrates the circuit connection employed in one embodiment ofthe present invention as applied to an electric locomotive transformer, Fig. 2 is a partial enlarged elevational view, partially broken away to show normal 1y hidden portions of the structure, of a tap switch and of the -means for operating the same according to the present invention,

Fig; 3is a sectional view taken on the line AB of Fig.2, 1 7

Fig. 4 is a fragmentary sectional view taken on the line GD of Fig. 3 and showing a portion of the circularly arranged fixed contacts and the movable contacts mountedin their carriages for rotation over the fixed contacts and Fig. 5 is a section taken on the line EF of Fig. 4 and showing the means by which the movable contacts are supported to obtain a uniform pressure on the fixed contacts.

Referring more particularly to the drawings by characters of reference, thereference numeral 6 designates a supply or trolley line from which current is taken by a current collector 7 through a main switch 8 to the winding of an auto-transformer 9. The winding 9 is tapped as at 9a, 9b and 90 and is grounded at 11. The-auto-transformer 9 supplies current to a second auto-transformer 12 which, for the purpose of economizing of space and of reducing weight,.is combined with the auto-transformer 9 so that the two auto-transformers have a common return Autotransformer 12 supplies current to a traction motor 13 controlled by a switch 14 connected across a portion of the windings thereof as is well-known. The taps 9a, 9b'and 9c are condrives a gear :33 meshing with a worm 34.

The worm drives the means carrying the movable contacts as will be described hereinafter.

In operation, when switch 8 is closed, contacts 36 and 37 of switch 17 being in the position shown and switches 22 and 23 also being in the posit-ion shown, current will flow from line 8 over current collector 17, switch 8 to winding 9 and to ground 11.

Operation of the motor 32 will cause move.

ment of switch 17 and contact 36 will be moved to tap 95 while contact 37 will remain on tap 9c. Switches 22 and 23 will both be closed. Current then flows from tap 90 over fixed contact 19 and switch 23 and also from tap 9?) over fixed contact 18 resistance 21 and switch 22.

From the connection between switches 22 and 23, current will flow through the winding 12 to ground 11 and from the winding 12 through the traction motor 13 and switch 14 to ground 11. Further movement of switch 17 moves contact 36 farther over tap 9b and causes contact 37 to leave tap 90. Switch 22 remains closed but switch 23 is opened. Current then flows through tap 9b, fixed contact 18, resistance 21, switch 22, winding 12 to ground 11 and from winding 12 through the motor 13 to ground. Continued movement of switch 17 brings contact 37 on tap 96. Switch 23 is also closed. Current flows from tap 96 over fixed contact 19, switch 23, winding 12 to ground 11 and from winding 12 through the traction motor 13 and to ground. The last portion of the movement of switch 17 moves contact 36 from tap 9?) and moves contact 37 farther over tap 9?). Switch 22 will be opened and switch 23 will be closed. Current will flow from tap 95 over fixed contact 23 and winding 12' to ground 11 and from winding 12 through motor 13 to ground. It will beseen from the above that changing from one tap to another does not interrupt current to the motor at any time and that the taps are changed under such conditions as to avoid sparking atthe contacts.

The present invention being particularly concerned with the mechanical construction of switch 17 by which the above described movement of contacts 36 and 37 is obtained will now be described in detail. In Fig. 2, 41 represents a housing, having the front thereof removed, which housing is arranged to be secured upon the tank containing the auto-transformers 9 and 12. The taps 9a, 9b and 9c are arranged to be brought out of the housing through bushings 42 as shown in Figs. 3 and 5 particularly and are arranged in a circle within which are the circular continuous fixed contacts 18 and 19.

A stationary shaft 43 is secured at the center of the concentric circles formed by the fixed contacts and carries a disc 44 on ball bearings 46. The disc carries a plurality of,

carriages 47 and 48 which are substantially triangular in form and are each suspended from the disc, by means of plates, by three bolts 51, 52, 53 and 56, 57, 58 with springs as at 59 about each bolt and compressed between the carriages and the plates. Each carriage, in addition to carrying one of the movable contacts 36 or 37, is also provided with a roller 61 and 62 respectively moving on one of the continuous contacts 18 or 19. The movable contacts and the rollers are preferably mounted in ball bearings to reduce wear on the fixed contacts. The carriages are thus each resiliently connected to a plate suspended from the disc by a three-point suspension and ride, at three points, over the fixed contacts. A uniform pressure on all the contacts is thus obtained. WVhen contacts 36; 37 leave one of the fixed taps 9, the carriages 47, 48 oscillate about their points of contact with the continuous fixed contacts 18, 19 within limits fixed by the heads of bolts 53 and 58. Contacts 9 are slightly chamfered to permit contacts 36 and 37 to mount and leave the taps with a minimum of disturbance in the rotary movement of the disc.

The edge of the disc 44 is provided with pins bearing rollers 63 extending radially from the disc. The rollers 63 are adapted to engage with a worm 64 mounted in the upper portion of the housing 41. The worm is in the nature of somewhat more than single turn of a distorted thread i. e. has edges of varying inclinations bearing on the rollers 63 so that the disc 44 will be rotated at varying speeds dependent on the position of the worm. The worm is formed with gear teeth on the outer periphery thereof which teeth mesh with a gear 66 driven from the motor 32 through the shaft 31:

The end of the shaft 31 is provided with a gear 71 keyed thereon and having a boss and a crank pin formed therewith. A small gear 75, engaging with gear 71, is attached to the shaft by means of a friction coupling 72. The

crank pin is fastened by spring 73 with a switch 74 leading to an alarm circuit or the opening circuit (not shown) of the switch 8. The switch 74 is under the tension of a spring 76 which positively closes the switch upon failure of the spring 73.

As mentioned above, shaft 31 operates circuit breakers 22 and 23 through the action of the cams 28 and 29 shown in Fig. 1. The operation of the motor 32 is controlled as is usual in tap switches for which purpose shaft 31 will be provided with suitable auxiliary contacts and interlocks as required.

As previously described, the worm 64 has edge portions of varying inclinations and also has entirely flat edge portions between the steeper portions and at both ends of the curved surfaces. The worm thus has four neutral or dead point portions during which i The space between the first and the last roller i. e. the rollers 360 away from the roller in contact with the worm 64 when contact 37 is on tap 9c, isclosed by a stop 77 to mechanically prevent over-travel of the disc 44 beyond the last contact in one direction or the first contact in the other direction in case the electrical interlocks usual with motors such as the motor 32 fail to operate.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

The invention claimed is:

1. In a switch for the step-wise making and breaking of electric circuits, a plurality of interrupted fixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts, and means for moving said rolling contacts in steps over said fixed contacts.

2. In a switch for the step-wise making and breaking of electric circuits, a plurality of interrupted fixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts, a disc mechanically connected with said rolling contacts, and means connected with said disc for rotating the same in a step-by-step manner.

3. In a switch for the step-wise making and breaking of electric circuits, a plurality ofinterruptedfixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts, adisc connected with said rolling contacts, a worm engaging the edge of said disc to move the same step-by-step upon continuous rotation of said worm, and means for rotating said worm.

4. In a switch for the step-wise making and v Y breaking of electric circuits, a plurality of interrupted fixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts, a disc connected with said rolling contacts, a worm engaging the edge of said disc to move the same stepby-step upon continuous rotation of said worm, said Worm havingportions of varying inclinations connected by portions not inclined, and means for rotating said worm.

5. In a switch for the step-wise making and breaking of electric circuits, a plurality of interrupted fixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts, a disc connected with said rolling contacts, and meansconnected with said disc for rotating the same in step-by-step manner, and means for returning said rolling contacts and said disc to dead points during each rotation of said worm.

6. In aswitch for the step-wise making and breaking of electric circuits, a plurality of interrupted fixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts, a disc con nected with said rolling contacts, a worm engaging the edge of said disc to move the same step-by-step upon continuous rotation of said Worm, said worm having portions of vary ing inclinations connected by portions not inclined, means for rotating said worm, and means for returning said rolling contacts and said disc to dead points during each rotation of said worm, the last mentioned of said means operating upon engagement of said disc with the uninclined portion of said worm.

7. In a switch for the step-wise making and breaking of electric circuits, a plurality of interrupted fixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts, a disc connected with said rolling contacts, a worm engaging the edge of said disc to move the same step-by-step upon continuous rotation of said worm, means for rotating said worm, and a tension spring connected with said worm rotating means to return the same to the initial position upon cessation of the movement thereof.

8. In a. switch for the step-wise making and breakingof electric circuits, a plurality of interrupted fixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts, a plurality of carriages retaining said rolling contacts in a pre-determined relation with said fixed contact, a disc resiliently supporting said carriages therefrom, and means connected with said disc for rotating the same in a step-by-step manner.

9. In a switch for the step-wise making and breaking of electric circuits, a plurality of interrupted fixed contacts arranged in a circle, a plurality of continuous fixed contacts arranged in a circle, contacts for rolling movement over said fixed contacts,a' plurality of carriages retainlng SitldlOlilIlg contacts in a pie-determined relation with said fixed contact, a. disc resiliently supporting said carriagestherefrom,rollers extending radially from the edge of said disc, a worm engaging; said rollers to move said disc in stepby-step manner, and means for continuously rotating said worm.

10. In a system for varying the connections of electric circuits, a switch capable of stepby-step movement, means for operating said switch, aplurality of circuit breakers, and means for causing opening or permitting closing of said circuit breakers, the last said mean being operated by the first said means.

11. In a system for varying the connections of electric circuits, a switch capable of stepby-step movement without interruption of the circuits, continuously rotatable means for operating said switch, aplurality of circuit breakers, and means for causing opening or permitting closing of said circuit breakers, the last said means being operable by the first said means.

In testimony whereof I have hereunto subscribed my name this 19th day of May, A. D.

ARNOLD HALLER.

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